Add generic linters

[dmohns]

This PR adds basic linter Github Actions that is commonly used in our repos to this repo. Next to some smaller fixes to the existing code base to make the linters pass.

[alchalade]

@dmohns can you squash your commits, as its hard to follow them ?

[dmohns]

Hey @alchalade

Most of the commits were added after rebases. The repositories is configured to allow only Squash&Merge anyways, so having lot of commits in a PR is not really an issue.

However, of course, if this make it easier for you to review, I can "pre-suqash" the commits on the PR already.

[dmohns]

Had a quick look at squashing... It's gonna be a lot of effort to squash this PR prior to merge, as there are ton's of merge conflict due to how old this PR already is.

Any objections to leave this as is? Anyways the code change, as in number of lines and file changes is small.

[alchalade]

@dmohns sure, I understand it.
Could be use rebase strategy instead of merge when bringing the feature branch on top of master/main? This will basically remove the unrelated commit history.
I'll review it in the afternoon.